1. Field of the Invention
The present invention relates generally to a device for locating lost articles, and more particularly, to a portable locator device that communicates with a transceiver through radio frequency signals to determine the relative distance and/or direction of the transceiver from the locator unit.
2. Description of the Related Art
Many devices have been proposed for the location of various types of objects. Most of these devices are limited to tracking a certain type of object, such as a child or a set of keys, or are confined to only occasional uses. Many of these devices are also limited in their range of applications due to such limiting factors as operating range, battery life, or the inability to selectively locate large numbers of different articles.
For example, the inventions described by U.S. Pat. No. 5,289,163 issued Feb. 22, 1994 to Perez, U.S. Pat. No. 4,785,291 issued Nov. 15, 1988 to Hawthorne, U.S. Pat. No. 5,900,817 issued May 4, 1999 to Olmassakian, U.S. Pat. No. 5,652,569 issued Jul. 29, 1997 to Gerstenberger et al., U.S. Pat. No. 6,127,931 issued Oct. 3, 2000 to Mohr, or U.S. Pat. No. 4,785,291 issued Nov. 15, 1988 to Hawthorne, generally relate to a form of an electronic leash for child monitoring.
These devices require the caregiver to activate the caregiver's monitoring device and child's transceiver device, and attach the transceiver to the child so that the child may be located if the parent and child become separated. While such devices may be useful in some circumstances, such as a shopping trip or a visit to the park, it is well known that children may wander away from their caregivers at any time without warning. If the child's transceiver device has not been activated before the child wanders away, the transceiver cannot be located by the caregiver's device.
Additionally, these systems rely on relatively constant communications between the child's transceiver device and the monitoring device. The need for constant communications between the transceiver and monitoring device disadvantageously requires the consumption of a large amount of power from the transceiver's battery. As a result, the transceiver may not have usable battery power at critical times in which the parent desires to locate the child.
Another class of locator devices is described, for example, in U.S. Pat. No. 5,939,981 issued Aug. 17, 1999 to Renney, U.S. Pat. No. 5,294,915 issued Mar. 15, 1994 to Owen or U.S. Pat. No. 6,166,652 issued Dec. 26, 2000 to Benvenuti. In general, these locator devices include a radio transmitter that is used to activate a radio receiver attached to an article, such as a television remote control or set of keys. When the receiver is activated, it emits an audible signal that alerts the user to location of the article to which the receiver is attached. Unfortunately, these systems are only useful over a relatively small area due to the limited range of the audible signal.
Accordingly, there is still an unfulfilled need for an article locator system that is power efficient, able to selectively locate multiple articles, and able to accurately locate articles beyond the immediate area of the locator device.